Well, it kind of depends on what dualism one espouses. This article argues that some people are what are called substance dualists: there are two kinds of stuff in the world one which known and understood, the physical (and this is false) and one which is not understood the mental or spiritual.
I've said this too many times here to go into details again, but, first of all, this physical stuff which is claimed is known so well, isn't, we postulate 95% of the universe as being made of dark matter and dark energy, we don't know what they are, but if we don't postulate that, then the 5% we can describe, doesn't hold.
If you then actually examine what the evidence says, you discover that physical stuff is waaaay stranger than our intuitions of it being "solid, touchable stuff", in fact, it's almost completely insubstantial.
What's also insubstantial, that is, not touchable and strange? The mind, which we don't know much about, other than we have it and are acquainted with it better than anything else.
So out the window with substance dualism. Now we have the world, with many properties (the mental, the biological, the chemical, the sociological). So one can be a monist-pluralist and say there's many kinds of things which are at bottom made of the same stuff, or you can artificially say that the mental is not physical and somehow has to be fundamentally different from the rest of the world.
Nothing follows if there is another life after this one in terms of monism.